I second the advice on the SL66. Optics are the same as Hasselblad but cheaper. They do not need maintenance also since they have no shutter or helicoid. Only once with my 150mm lens I had the aperture to be fixed. A great advantage is the seamless close up focusing. If you want to use the older lens designs like 80mm/120mm Planar or 150mm/250mm Sonnar I would favour the Rollei. The 50mm lens is also very good once stopped down. However, the Rollei ist more heavy and bulky compared to a 500cm. You will need a stury tripod.